How do I change screen brightness?

Laptop

How do I change screen brightness?

Some months ago I was browsing somewhere among the menus of my Inspiron 1200 (XP Home with SP2), and I found a setting for changing screen brightness to save battery power, in 10% increments. I dimmed it a few stops, and tried it for a while.

I finally decided that the screen is now too dim, so I tried to set it back to where it was. But I can't find a brightness setting anywhere. Where did it go?

I looked, of course, in Control Panel, under Power Options and under Display. There is nothing under any of the tabs in either of those locations. Where did I leave that switch?